Hacksaw blade tensioning device



June 3, 1952 Filed Jan. l0, 1947 D. E. GOMMEL HACKSAW BLADE TENSIONING DEVICE 2 Sl-IEETS--SHEET l June 3, 1952 D, EI GOMMEL 2,598,784

I HACKSAW BLADE TENSIONING DEVICE Filed Jan. lo, 1947 2 SHEETS-SHEET JNVE/vroze. DEWEY E. Gon/MEL,

A TTOZNE'K Patented June 3, 1952 IMGKSAW BLADE TEN SIGNING DEVICE DeweyE. Gommehlndianapolis, Ind., assignor to E. G. Atki'nsf andy Company', Indianapolis, Ind.,V

acorporation of Indiana Application January 10, 1947., Serial No.A 721,386

of the invention is yto provide. such means whichl shall be readily adjustable to varythe degree of tension applied to the blade, to compensate for varia-tionsl in blade length, and to be readily readable, upon inspection, whereby the operator may readily ascertain the degree of tension under which the blade isoperating at the moment. Another object is to provide such means adaptable for use in various types of commercial hack sawv machines.

Further objects ofv the. invention will appear as the description proceeds.

To the accomplishment of the above and relatedy objects, myA invention may be embodied in the forms illustrated in the' accompanying drawings, attention being called to the fact, however, thatv the drawings are illustrative only, and that change may be made in the speciiic constructions illustrated' and described, so long as the scope of. the appended claims is not violated.

Fig. 1' is a fragmental view of one standard form' of mechanical hack saw, with my improved tensioning meansY applied thereto;

Fig. 2. is, an enlarged fragmental elevation of a tensioningy mechanism, the resilient means thereof being shown in section for clarity of i1- lustration;

lig.y 3- is an end elevation ofthe parts shown in Fig. 2, as viewed from the right of Fig'. 2;

Fig. 4 is a tcp plan view of my` improved resilient means;

Fig; 5 is a fragmental elevation of the draw stud and associated parts of another form of hack saw machine, with a different embodiment of my tensioning device associated therewith;

Fig. 6 is an enlarged end elevation taken from the right of Fig. 5;

Fig; '7 is a view similar to Fig. 5, showing a further embodiment of my invention;

Fig. i3Y is an enlarged end elevation taken from the right of Fig. 7; and

Fig. 9 is a view similar to Fig. 5 but showing a still further form of my tensioning means.

Referring more particularly to the embodiment of my invention shown in Figs. 1-4, it will be seen that I have shown a standard type of mechanical hackv ,saw including a reciprocatingv frame comprising a body member l provided (Cl. 14S- 156) a guide l'- upon the body memberi I0 for ad justment: toward and away from the stud Hf. The element L3' may preferablyY be formed with a: longitudinally spaced seriesV of openings'r l5 therethrough, and a lever I6, which may preferably be in the form ofa` yoke, as isclearly shown in Fig. 3, is mountedv upon the element I3 and pivotally associated.l therewith through the medium of a pin I1V passing through aselected one of the openings l5.

One end I8- of-thelever lliv carries athreaded' bolt I9 provided with a polygonal head l2llwhereby said' bolt may be adjusted relative, to said leverk end i8. The bolt head 20- is adapted to bear against the frame body member I0- and,

if desired, it may be hel'd against accidentaldis-- placement with respect to saidbody member by means of apin 2l received' inaligned soclietsv in said body member and said.' bolt' head.

The opposite end 22 of theV lever' l`6- likewise carries a bolt or screw 23, threadedly adjustably associated with said lever andl adapted to bear against resilient means which may preferably takeV the form off theA unit' indicated generally by the referencey numeral 24.

Said unit comprises'a barrel 25- having a closed end 26 and an open mouth' 21'. Projecting radially froml said barrel, and preferably rooted at or about said mouth 2T, is a linger 28 which is inclined from a plane normal to the axis of the barrel 25', so that its rounded distal end 29 is positioned forwardl'ypbeyond said barrel mouth 2l. A spring 30 is received in the'barrel 25, one end thereof abutting thel closed end ofl said barrel and the otherV end bearing against a plunger 3| axially reciprocabl'y-mounted in said barrel 25. The spring V3!! issoproportioned and designed that, when in equilibrium, andy withA one end abuttingv the barrel end 2-6', its opposite end will project beyond the barrel; mouth 2l; and said. spring" resists. movementy oil the plunger 3| toward said closed end 26 of the barrel.

The nose of the screw'2`3 engages in a suitable socket 32 formed. in that Surface of thenger 28 which is remote from the bodyV member lil when the. unit 24 is interposedl between said body member' and theY screw 23. Said. socket` 32 is formed intermediate the ends of the; iinger 28Y and preferably closerbto the distal enr-,L29 thereof' than to the barrel'4 25. Y,

It will be clear that, when one end of a blade Bis hung on the stud I I and the other end thereof is engaged with the stud I2, tension can be applied to said blade by applying force to the element I3 in a direction toward the right as viewed in Figs. 1 and 2. The lever I6 having been associated with the proper opening I5, the screw I9 may be adjusted to bring the end I8 of said lever directly below the pin II. If, now, the unit 24 is interposed between the body member III and the screw 23 in the manner shown in Figs. 1 and 2, it will be seen that adjustment of the screw 23 to produce movement thereof toward the left relative to the lever end 22 will apply such force to the element I3. Such adjustment of the screw 23 applies a corresponding degree of force to the linger 28, tending to rock the unit 24 in a counter-clockwise direction about the point of engagement of the rounded finger end 29 with the body member ID, against the tendency of the spring 35. Because of the relative position of the point of'engagement of the screw with said finger, the actual quantum of force applied to the spring 30 is minimized. Therefore, compression of said spring 30 through relative movement of the barrel 25 and the plunger 3I is extremely small per hundred pounds of pressure applied by the screw 23 to the iinger 28. Preferably, the plunger 3I will be provided with graduations 33 so calibrated as to indicate to the operator, when read against gagement by the unit 24, primarily because of the fact that a slight vertical movement of the rounded head of the plunger 3I must result from rocking movement of the unit 24 about the end 29 of the finger 28, and therefore the unit 24 should engage a smooth and very hard surface, which will not always be found on the end of the body member lli.

Preferably, but not-necessarily, the finger 28 will be perforated at 64 to pass a headed Vstud 65 preferably threadedly associated with the pillow block 34 and projecting therefrom in the manner clearly illustrated in Figs. l and 2. If the blade B breaks at a time when heavy tension is applied thereto, the unit 24 will, unless restraining'means therefor is provided, iiy violently away from the frame I3 underthe inuence of the suddenly-released energy of the spring 30. The perforation 64 being smaller than the head of the stud 55, that stud will, of course, restrain the unit 24 in such a contingency.

In Figs. 5 and 6, I have shown my tensioning n device associated with a different type of hack saw machine in which the frame, a fragment of which is indicated by the reference numeral I0', provides a iixed mounting for one end of the blade B, and provides a cylindrical slideway I4 in which is reciprocably mounted an element I3' carrying a stud I2 upon which is engaged the other end of the blade B. In standard practice, the outer end of the element I3 is threaded, as at 35, for the reception of a nut which is intended to bear directly against the frame member I3 to apply tension to the blade B. According to the present invention, a compression member 36 is slidably mounted on the outer end of the member I3' and is formed, preferably, with knife. blades 31 at its opposite sides adapted to cooperate with the tensioning unit 24. Said unit is closely similar to the unit 24 of Fig. l, compris- 4 ing a barrel 38 having a bottom 39 formed with an axial port 40 therethrough, and having an open mouth 4I. A finger 42 projects radially from the barrel 38, being rooted near the mouth of said barrel, and being inclined to a plane normal to the axis of the barrel, so that its distal end 43, which may preferably be sharpened, as shown, is displaced forwardly from the plane including the barrel mouth 4I and normal to the axis of said barrel. A spring 44 is received in the barrel and is confined between the bottom 33 thereof anda plunger 45, reciprocably mounted in said barrel. The plunger 45 may be calibrated in the manner, and for the purpose, described in connection with the unit 24. A headed stem 43 is reciprocably mounted in the port 49, one end thereof being threadedly engaged with the plunger 45, and the opposite end thereof extending beyond the barrel bottom and being provided wit an enlarged head 4I dimensioned to prevent its passage through the port 4U. It will be obvious that the stem 46 limits Voutward movement of the plunger 45.

A nut 48 is threadedly mounted on the threaded end 35 ofthe element I3 and backs up the element 33. It will be clear that, as the nut 48 is turned up on the element I3', greater and greater tension will be applied to the blade B, and the spring 44 will be compressed to a degree directly proportional to the tension thus applied to the blade. I presently prefer to form the finger 42 with V-shaped sockets 49 to receive the blades 3l; and I further prefer to provide a restraining stud 65 which, in this instance, is shown threadedly associated with the frame III.

In Figs. 7 and 8, I have shown a further modification of the tensioning means included in my invention. In some machines the outer face of the body member I0 is not flat but is formed with depressions 50, or thelike. For use with such machines, I provide a pillow block 5I adapted to .bridge any such depressions, and if necessary,v to projectbeyond the frame, as shown to provide a suitable surface against which the parts of my invention may engage. In the illustrated embodiment, the pillow block is formed with an outward projection 52. A rocker 53 is slidably and rockably mounted on the projecting end of the element I3 and is formed, at one end, with a toe 54 rockably engageable with the projection 52 of the pillow block 5I. Intermediate its ends, the rocker 53 may preferably be provided with an outwardly projecting protuberance 55 against which engages a washer 33' backed up by a nut 48 threadedly mounted on the threaded end 35 of the element I3'. Adjustably mounted in the opposite end of the rocker 53 is a screw 56 which will preferably be provided with a lock nut 5i. Said screw 56 bears against the finger 42, preferably at a point nearer to the toe 43 thereof than to the barrel 38. Obviously, adjustment of the tension of the blade B may be effected either by adjust-ment of the nut 43 or by adjustment of the screw 56, or both. As in the previously-discussed embodiments of my invention, I show a restraining stud 65, here threadedly associated with the block 5 I.

In Fig. 9 I have shown a still further arrangement of parts in which a post 58 projects from the body member I0' upon an axis substantially parallel to the axis of the element I3. A rocker 5S, formed with a part cylindrical protuberance BIJ intermediate its ends, has one arm 6I movably associated with the post 58 and its opposite arm 62 movably associated with the element I3. A

nutL 631, tlireadedly mounted on the thrdadi-Sd.endy Se? ofvv sai'd element I3 bea-rsagainsttlierocle'i:` arm 62' to" limit its movement' relativetothe element l'3-"i'no'ne' direction, A member `3i-,i'rlilalll respectsL like the member 318i of Figs and 6`, is" sl'i'dably associated withthe post 58 and bears' against thetnger :'Zintermediate the endsi there'-v of, the-toe`A of said ringer and the plunger 451 of! the unit"v dvbearing against spaced points-von thel arm 6l of tlierocker 692 The tension ofthe-blade? B, in thisassembly, be adjusted by" adjustment-otthe nut 63lor o`fthe nut' 18, or. bothLof: them. A stud 65, this instance shown to. be: threadedly associated with the rocker 59, may.' be used to restrain the unit Zi' in the' manner herei-nbeforeeri-plained.-

Inl all forms of the' invention, at mechanical advantage is` conferred: upon the spring by th'e leverage prcnffided, so thatY standard springs may be used to apply heavy tension upon the blades. it will be noted that where multiple leverages are used, asin the embodiments of Figs. 7 and 9, the point ofr pressure application upon the ngeris closerv to the barrel than in the more direct appli'- cation'` as in-Figlb. This point of pressure appli-v cation, in eaciiinstance', is preferably so calculatedthat one standardis'pring and one standard cali-y bration or the plunger will be applicable in anyr one of the illustrated embodiments of my invention.

I claim as my invention:

l. A` hack saw frame' comprising a body mem-- ber, retaining means carried by said body member and engageable with one end of a blader an element shiftably supported on saidr body membei` ior movement toward and away from sai-d retaining means, holding means carried by said element and engageable with the other end of such blade, a lever operatively connected with said element for movement relative thereto, means limiting movement of said lever in one direction relative to said element, a tensioning device com'- prising a iirst'- member and a second member and a spring tending to separate said members, an arm projecting from said first member, said armi and said second member bearing against relatively spaced points on said body member adja-A cent said element, and means threadedly associated with said lever and engaging said arm intermediate the points of engagement of said arm and said second member with said body' membei.

2. A hack saw frame comprising a body member, retaining means carried by said body niember and engageable with one end of a blade, an element shiftably supported on said body member for movement toward and away from said retaining means, holding means carried by said ele-` ment and engageable with the other end of such blade, Aa lever pivotally secured to said element having portions respectively projecting oppositel'y thereb'eyond, means threadedly associated with each projecting portion of said lever, one of said last-mentioned means engaging said body member, and resilient means interposed between the other one of said last-mentioned means and said body member, said resilient means comprising an elongated member having a portionof one face in contact, adjacent one end, with said body member and spring means interposed between the body member and said face adjacent the other end, said other one oi said means en-I gaging' the opposite faceof said elongated means intermediate saidl ends.

3. A- hacksaw' frame comprising a bodymemthreadedly associated with the projecting portion off sai'dilever, and resilient means interposed betweensai'd sore-w and said body member, said res'ilienty means comprising an elongated member havingaportion of one face in contact, adjacent 1 one' endl, with saidbody member and spring means interposed between the' bodyV member and said f'a'ee adjacentlthe other' end', said screw engaging the' opposite` faceV off said elongated means intermediate said ends.

v i hack@ sawy frame' comprising a body' member; retaining' means carried by said body member' andi e'ngageable with one end of a blade, an element shiitablysupported on said body member' iovementteward and away from said retainmeans, holding means carried by saidV elemeritiand engageable" with the other end' of said bladeiimeans: projecting angularly from said element, a" serew threadedly adjustably carried by sai'd projecting means upon an axis substantially parallel with the line of movement of said elemeritfandlresilient means interposed between said *said body' member', said resilient means rising" anelongatedmem-ber having a portion oione face supported' adjacent one end, by said body" rnember, spring means interposed betweenf the body member and said face adjacent other end', sai'd screw engaging the opposite face of said elongated means intermediate said ends.

5;- Ei hacks`aw` frame comprising a body member', aistud? carried byv said bod-y member and engage'able with one end of a blade, an element shiitab'lyl supported on said body member for movementtoward and away from said stud and carrying asecond-studengageable with the other end of' said blade, means projecting angularly from said element, a screw threadedly adjustably cs'trriedl by said-y projecting zneans upon an axis substantially parallel with the' line of movement of said element, and resilient means interposed betv'5jreenV said screw' andv said body member, said resilient means comprising a barrel having a bottoni and an openmouth, a nger rooted subn stanti'ally' at the mouth of said barrel and projecting-radially andlforwardly beyond said mouth -atn ang-le' to the' plane of said mouth which is al to the airis of said barrel', a plunger axially' neoiprooabl'y mounted in said barrel, and a spring.' received' in said barrel and confined between the bottom thereof and said plunger, said spi-ing resisting movement of. said plunger todi the bottom of said barrel, the distal end of` aid finger and. said plunger bearing against said-body' member, andrsaid screw bearing against that face of said finger remote from said body member andIV intermediate the ends of said nger.

6. hack Saw frame comprising a body member', a stud carried by said body member and engageable with one end of a blade, an element shiitably supported on saidV body member for movement'toward and ziwayV from said stud and carrying a second stud engageable with thev other end of said blade, means' projecting arigularly` from said'element,I a' screw'threadedly adjustaoly carried by' said projecting means upon an axis substantially Vparallel with the line of movement of said element,V and resilient means interposed between said screw and said body member, said resilient means comprising a barrel having a bottom and an open mouth, a finger rooted substantially at the mouth of said barrel and projecting radially and forwardly beyond said mouth at an angle to the plane of said mouth which is normal to the axis of said barrel, and spring means carried in said barrel and having a relaxed length greater than the depth of said barrel, the distal end of Vsaid linger being rockably associated with said body member and Ysaid spring means being supported bysaid body member, whereby the intermediate portion of said linger is spaced from said body member, and said screw bearing against that face of said linger remote from said body member at a point intermediate the ends of said finger.

7. As an article of manufacture, a blade tensioning device comprising a barrel having a bottom and an open mouth, a finger projecting radially from said barrel and inclined to a plane normal to the axis of said barrel so that the distal end of said finger is located forwardly beyond said barrel mouth to serve as a rocking fulcrum for said barrel, and a coiled spring received in said barrel, abutting the bottom thereof, and having a relaxed length greater than the depth of said barrel.

8. As an article of manufacture, a blade tensioning device comprising a pair of telescopicallyassociated elements, a spring confined between said elements and resisting collapsing relative movement thereof, and a finger projecting radially from one of said elements and inclined from a plane normal to the common axis of said elements.

9. As an article of manufacture, a blade tensioning device comprising a barrel having a bottom and an open mouth, a plunger axially reciprocably mounted in said barrel, a spring received in said barrel, confined between the bottom of said barrel and said plunger, and resisting inward movement of said plunger, and a linger projecting radially from said barrel and inclined to a plane normal to the axis of said barrel so that the distal end of said finger is located forwardly beyond said barrel mouth to serve as a rocking fulcrumY for said barrel.

10. .As` an article of manufacture, a blade tensioning device comprising a barrel having a bottom formed with an axial port therethrough and an open mouth, a plunger axially reciprocably mounted in said barrel, a headed stem reciprocably mounted in said port and connected to said plunger, the head of said stem being located outside said barrel and being dirnensioned to prevent its passage through said port whereby said stem limits movement of said plunger away from said barrel bottom, a spring received in said barrel, confined between said barrel bottom and said plunger, and urging said plunger away from the bottom of said barrel, and a finger projecting radially from said barrel and inclined to a plane normal to the axis of said barrel so that the distal end of said finger is located forwardly beyond said barrel mouth to serve as a rocking fulcrum for said barrel.

11. A hack saw frame comprising a body member, retaining means carried by said body memier and engageable with one end of a blade, an element shiftably supported on said body member for movement toward and away from said retaining means, holding means carried by said element and engageable with the other end of such blade, a tensioning device comprising an elongated member having a portion of one face rockably associated, adjacent one end, with said body memberand spring means interposed between said body member and said face adjacent the other end of said elongated member, and means operatively associated with said element and adjustable relative thereto substantially in the direction of movement of said element, said last-mentioned means engaging that face of said elongated member remote from said body member, intermediate the ends of said elongated member.

12. A hack saw frame comprising a body member, retaining means carried by said body member and engageable with one end of a blade, an element shiftably supported on said body member for movement toward and away from said retaining means, holding means carried by said element and engageable with the other end of such blade, a tensioning device comprising a barrel having a bottom and an open mouth, a finger projecting from said barrel and inclined to a plane normal to the axis of said barrel so that the distal end of said finger is located forwardly beyond the open mouth of said barrel for bearing against an abutment surface supported from said body member, a coiled spring received in said barrel and confined between the bottom thereof and an abutment surface supported from said body member, and means associated with said element and adjustable to move relative thereto in the direction of movement of said element, said last-named means bearing on said finger to urge said tensioning device toward said body member against the tendency of said spring.

13. A hack saw frame comprising a body member, retaining means carried by said body member and engageable with one end of a blade, an element shiftably supported on said body member for movement toward and away from said retaining means, holding means carried by said element and engageable with the other end of such blade, a tensioning device comprising a barrel having a bottom and an open mouth, a nger projecting radially from said barrel and inclined to a plane normal to the axis of said barrel so that the distal end of said finger is located forwardly beyond the open mouth of said barrel for bearing against an abutment surface supported from said body member, a plunger reciprocably mounted in said barrel and projecting beyond the open mouth thereof for bearing against an abutment surface supported from said body member, a coiled spring received in said barrel and conned between said barrel bottom and said plunger, the free endof said elementbeing threaded, a nut adjustably mounted on said threaded end, and means interposed between said nut and Said nger to urge said tensioning device toward said body member against the tendency of said spring.

14. A hack saw frame comprising a body member, retaining means carried by said body member and engageable with one end of a blade, an element shiftably supported on said body member for movement toward and away from said retaining means, holding means carried by said element and engageable with the other end of such blade, a tensioning device comprising a barrel having a bottom and an open mouth, a finger projecting radially from said barrel and inclined to a plane normal to the axis of said barrel so that the distal end of said nger is located forwardly beyond the open mouth of said barrel, a plunger reciprocably mounted in said barrel, a coiled spring received in said barrel and confined between said barrel bottom and said plunger, the free end of said element being threaded, a rocker traversing said element, a nut adjustably mounted on said threaded end and bearing against said rocker, a pillow block traversing said element and bearing against said body member, one end of said rocker being rockably associated with said pillow block, the distal end of said finger and said. plunger likewise bearing against said pillow block, and means adjustably associated with the other end of said rocker and bearing against that surface of said finger remote from said pillow block intermediate the ends thereof.

15. A hack saw frame comprising a body member, retaining means carried by said body member and engageable with one end of a blade, an element shitably supported on said body member for movement toward and away from said retaining means, holding means carried by said element and engageable with the other end -of such blade, a tensioning device comprising a barrel having a bottom and an open mouth, a finger projecting radially from said barrel and inclined to a plane normal to the axis of said barrel so that the distal end of said nger is located forwardly beyond the open mouth of said barrel, a plunger reciprocably mounted in said barrel, a coiled spring received in said barrel and conned between said barrel bottom and said plunger, the free end of said element being threaded, a rocker having an intermediate section rockably supported by said body member, one

end of said rocker being movably associated with said element, a nut threadedly mounted on the threaded end of said element and bearing on said one end of said rocker, a post supported on said body member in substantial parallelism with said element with its free end threaded, theother end of said rocker being movably associated with said post, said nger traversing said post, the distal end of said nger and said plunger engaging said rocker, and a nut threadedly mounted on the threaded end of said post and bearing upon said finger intermediate the ends thereof.

16. In the organization of claim 12, means xed with respect to said body member and operatively associated with said tensioning device to limit movement thereof relative to said body member under the influence of said spring.

DEWEY E. GOMMEL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

